Abstract
Contrary to Michael Miller, I maintain that Descartes’s language test adequately distinguishes humans from non-human animals, and that the bonobosKanzi and Panbanisha have not passed it. Miller accepts Descartes’s language test as a good test for true language usage, but denies that it is an adequate test for the presence or absence of reason. I argue that it is a good test for reason, for normal rational beings eventually recognize the desirableness of knowledge of the world for its own sake as well as the fact that such knowledge can be increased by conversing with others. I also argue that the tests administered to the bonobos in question are inadequate for determining true language usage, as they could be passed by animals merely capable of associative learning.